It sounds like you've found quite the money pit. This thread would benefit from the addition of TheGrimSqueaker.
[in my best Lurch voice] You rang?
There's a problem, gang: I recently exhausted my monthly supply of F-bombs on a different thread. I'll do my best but the simple fact is that it's no laughing matter.
Unlike PencilThinStache's mooch-tastic roommate, this aging gentleman isn't able-bodied with lots of future potential. He's in the twilight of his career, at a stage where most people his age have already built or otherwise earned the social, financial, and physical infrastructure that will support them as their bodies and minds slip into the inevitable decline known as old age. All that he has to work with, is what he's got right now. Which isn't much.
Nip, tuck, and supplement as we will, old age comes for all of us. Like Kenny Rogers famously said: "the best that you can hope for is to die in your sleep." For most people in an industrialized country, death comes at the end of an illness or long decline. You gradually set things aside or even lose them outright. Maybe one year it's a high-impact sport. Maybe another year it's a hobby that requires fine motor control and good eyesight, because you can't see as well as you used to. Eventually it's your driver's license. During this process, our physical labor becomes less valuable than it used to be. Our technical skills eventually become obsolete. Our knowledge of human nature, or of institutional memory, may still be sharp but a department or company only needs so many sages. So our economic productivity as income earners must necessarily peak, and then taper off.
Many societies revere the elderly and have room for them as caregivers for children or repositories of knowledge, however eventually it gets to the point where such people require ongoing care and resources from others just to stay alive. At that point, the elder must rely on whatever family, church, or government system is available, along with the resources he or she created earlier in life. For some, the support comes from the family and friends who are repaying favors done and sacrifices made during previous years. Others set aside financial resources. Still others have businesses or income producing assets that they own, which are administered for them by others for their benefit. It comes down to having some legitimate claim on others, and cashing in that claim. There is no other mechanism for human survival in old age, and there never has been.
This is a natural process. We make our beds, and then we lie in them. It has never been otherwise.
Let us now shift our focus from the general to the specific, and consider the plight of this 64-year-old. The critical forks in the path-- the opportunity to develop the kind of character and social skills that would allow him to be employable in the long term, for example-- are long behind him. He lacks a strong social support network because he did not plug into a healthy, supportive group of people and interact with them for years in a positive way, thereby earning the kind of social capital that leads to job offers, shared accommodation, or other help. In fact, he drains the people around him. The more people he drains, the more they pull away in self-defense; the more people pull away, the more he drains the ones who remain. Of course he's got some things going for him: that's how he lures people in close enough to... well, not take a bite, but get them to open a vein for a while.
Barring some last-minute introduction of a codependent willing to serve as a meal ticket for a while, this man truly has few legal options if he wants to continue at his present standard of living. He's been able to live above his real means for quite some time to allow for his present standard of living, which has been unsustainable for quite some time based on his work history and level of social skills.
A person who actually quits a job or is fired over a personality conflict or a bad fit a couple weeks in... is a person who hasn't learned to work with others or who lacks other basic pre-employment skills. By "pre-employment skills" I mean showing up on time, following instructions, interacting with other people in a way that is not belligerent, accepting feedback, taking responsibility for their actions, and following basic cultural expectations about appearance and hygiene. You see the problem a lot more in the teenage-to-early-20's set because people eventually grow out of it. They realize what is expected of them, start doing that thing, get rewarded for it, and learn how to function as an adult. Unless, of course, something interrupts this process which sounds like what happened to the 64-year-old many years ago.
(When I talk about quitting over a personality conflict, I'm not talking about quitting due to unsafe work conditions, illegal activity, or some misrepresentation in the offer, because that's a legitimate response to bad employer behavior. Bad employers do exist. However, they're not the norm. If this 64-year-old has had a series of "bad" employers, then chances are he's the problem.)
So, Frugalecon, my advice to you is this: your 64-year-old buddy is a vampire. Not the Count Dracula predatory kind... I'm talking about the kind of vampire that's created when someone is bitten, drained, and rises from the dead to drain others. He's been, in your words, "unreasonably generous" with other people. So he's opened his own veins, and been bled to the point where he no longer has enough for himself. There's a predictable consequence for this behavior, and you're seeing it play out in front of your own eyes.
Don't open a vein for this guy. You've given him the $1000, but you can see for yourself that it hasn't helped him. All it's done is create a precedent such that "no" will become harder. If you were to give him another thousand dollars, or even ten thousand dollars, a few months from now his problems will still exist, and you've surely realized that he's not going to pay you back. In fact, money you give to him is very likely going to be spewed out his other wounds, to nourish those for whom he's opened a vein in the past. The second you get his blood pressure up above, say, 90/60, he's going to feel strong enough to look around for someone else to share with. This is in his nature. When that recipient in turn begins to feed, your friend's blood pressure will drop again. The more you transfuse, the more he'll allow to be drained. He's a conduit to an infinite resource sink that can and will suck in all available resources, and then some. Your resources are finite, noble Frugalecon. So turn off the blood supply while you can unless you too wish to become a vampire. That would suck.
Your friend's problems will still exist a year from now, or even ten years from now, because he hasn't addressed their root cause and now it's probably too late. The root cause of this man's problem is a set of decisions made and habits developed so far in the past he'd need a time machine to correct them. Have you a time machine? Most likely not. (If you do, please let me borrow it, because I want to go back in time and hang out with Attila the Hun, Vlad the Impaler, and some other persons of interest.) So you don't have the power to help this man long-term unless you're willing to be his meal ticket and subsidize what sounds like some very poor life choices. But if you invite him into your home, especially to stay, you're going to be drained.
My advice to you is to understand and accept the limits of your power and take a massive step back. You don't have to drive a stake through his heart, but you do have to steer clear especially since he's pegged you as a source of money. Also, he's got some teeth: when you offered advice instead of the specific thing he wanted (money), he criticized you for being too "parental" and not "empathic" enough, and suggested that you had a lack of ability in the empathy department because any reasonable empathic person would have shelled out. This is not accurate, of course. It's just some punishment dished out to get you to comply. Standard behavior in parasites whose hosts are escaping: apply a bit of negative reinforcement to get them back in line so as to latch on again. If you allow it, you'll basically be agreeing with your friend that he, and not you, is the authority on how much and how often you ought to give to him. Which is bunk.
Your friend's only viable options for living mooch-free involve a large, voluntary, permanent reduction in his standard of living. He may have to take the Social Security early, and accept the permanent smaller checks. Or he could try for some other means-tested sources of help. Depending on the size of his apartment, he may be able to sublet or split the lease with a paying roommate (instead of someone who's mooching off of him). This of course will require him to be, or become, the sort of person who's worth paying to share accommodations with. He'll have to make some hard decisions and cut loose his existing couch surfer in order to make room for someone who really can help to pay the bills. But the evidence suggests that this guy doesn't make hard decisions. He just takes the path of least resistance and then blames astrology. ("The fault is not in our stars, dear Brutus, but in us, that we are underlings.") So he's most likely going to have to give up the apartment (rent-controlled or otherwise) and move to a place where housing is cheaper and he can cobble together a standard of living proportionate to his income.